Encryption: What Is It and How Does Encryption Work?

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Quick Guide: What Is Encryption? How Does Encryption Work?

Encryption refers to the process of scrambling plain text to make it unreadable using an algorithm. It is used to protect sensitive data, ensuring it is only accessible to the intended recipient.

There are different encryption protocols and algorithms with varying levels of security and sophistication.

Encryption is essential for online privacy and security. It guarantees data integrity. However, encryption can also be used to target users in ransomware attacks.

To safeguard your data and complement the encryption of any website, app, or digital platform you use, we recommend using a Virtual Private Network (VPN). A VPN encrypts your data, and routes your internet traffic through a different server, ensuring it is safe from all prying eyes.

NordVPN is our top-rated VPN. It offers military-grade encryptionadvanced security tools, fast speeds, and excellent performance.

To learn more about encryption and get in-depth understanding of how encryption works, continue reading this article!

Off the top of your head, can you count how many websites and apps have your credit card details and other sensitive information? How many times have you sent highly confidential files online? I bet it’s difficult to count.

Do you ever wonder how you can send such sensitive data over the internet without hackers and other unauthorized parties getting a hold of it? Well, that’s because of encryption.

Data encryption refers to the process of converting readable text into scrambled, incoherent data using an algorithm. Only the intended recipient can access the encrypted information.

In our VPN reviews and news stories, we often talk about encryption and the importance of keeping your data safe online.

But what exactly is encryption? What does “encrypted” mean? How does encryption work in VPNs? And why is end-to-end encryption important?

We answer these questions and more in this article.

What Is Encryption?

What is encryption iconEncryption is a way to encode data. It ensures your text isn’t readable by anyone but the person with the right encryption key.

A simple way to understand encryption is to compare it to secret, coded messages in which each symbol represents a specific letter. For example, an A may actually be a D, a B an E, a C an F, and so on.

If you understand the algorithm behind the code (i.e., what each letter represents) you’ll be able to read an encrypted text. Suddenly, the nonsensical, encrypted word “EBIIL” becomes “HELLO.”

Humans have used encryption for thousands of years to protect sensitive information from prying eyes. There’s evidence of primitive forms of encryption in Ancient Egypt, Greece, and Rome. Julius Caesar developed a basic form of encryption known as Caesar cipher to send messages to his troops during military campaigns.

Today, algorithms, which are also known as ciphers, are used to encrypt the data we send online. Your device or the platform you’re using decodes the encrypted data using a decryption key: a set of mathematical values agreed upon by the sender and recipient.

How Does Encryption Work?

Data encryption is possible due to the existence of digital encryption keys.

Think of encrypted data as documents in a locked safe. You can only access the documents if you have a key that can unlock the safe. If the safe falls into the hands of someone without the key, it won’t be of any use to them: the papers remain inaccessible and the information unreadable.

Based on this analogy, the sender of an encrypted file locks the safe (i.e. encrypts the data) with the cryptographic key. The recipient is only able to unlock the safe (i.e. decrypt the data) using a secret key.

It’s very important that the encryption key (the algorithm used to encrypt data) is chosen carefully. If this algorithm is too simple, other parties, such as cybercriminals, could easily crack it and decipher the sensitive data.

There are two primary methods of encryption: symmetric and asymmetric encryption.

Symmetric encryption

Symmetric encryption means the same key is used to encrypt and decrypt data. For this to work, both the sender and recipient must have the same secret key.

The biggest advantage of symmetric cryptography is that it’s very fast. It works quickly because the sender and receiver use the same encryption key. The most widely used symmetric encryption algorithm is the Advanced Encryption Standard (AES).

Symmetric encryption explained

Symmetric encryption is especially useful for data protection and transmission in small, closed networks. It works well when you want to exchange data in a safe and fast way.

Unfortunately, symmetric encryption has a major drawback: if the recipient doesn’t have the key yet, it has to be sent to them, just like the encrypted information. This allows others to intercept the key and read the messages. Hackers and internet criminals could easily take advantage of this.

Asymmetric encryption

Asymmetric data encryption is also known as public key encryption or public key cryptography.

This method of encryption works with two different encryption keys: a private key and a public one. The public key is used to perform the encryption. Everyone has access to this key, so everyone can encrypt data this way.

However, if you want to decrypt the data, you need a private key, which is linked to the public key. Only the receiver has access to the private key, meaning your data is protected from snooping eyes.

Asymmetric encryption

Generally, asymmetric encryption is considered a more secure option than symmetric data encryption. The chances of a leak are significantly less, although this method of encryption is slightly slower.

The fact that two different keys are used to protect data means it takes more time to encrypt and decrypt the information. Also, encryption key management can be a challenge as there are different keys.

Why Is Encryption Important?

Infographic showing why is encryption important

It’s not hyperbole to say that encryption is the bedrock of communication and transactions over the web. Here are some reasons why encryption is important:


Encryption ensures sensitive data is inaccessible to people who shouldn’t have access to it. When you encrypt sensitive data, you prevent the government, Internet Service Providers (ISPs), and others from monitoring your online activity and accessing your private information. Encrypting data at rest and in transit ensures that it can’t be breached at any point during its journey from you to the recipient.


Encryption guarantees no one can access or change the encrypted data while it’s in transit, unless the encryption key has been compromised. It ensures the data is accurate and intact.


Encryption protects private data and prevents it from falling into the wrong hands. Your data could be used against you in countless ways. For example, if a cybercriminal manages to get hold of your banking information, it could have all kinds of nasty consequences, including an empty bank account.

Regulatory compliance

Encryption allows large organizations to function without getting on the wrong side of the law and risking huge fines. If an organization like your healthcare provider were to leak your medical information because they don’t have proper data protection measures, they’d be in serious trouble with regulatory bodies.

Drawbacks of Encryption

Infographic showing drawbacks of encryption

While encryption is important for secure data transmission across the web, it has some minor drawbacks:

  1. Slows down data transfer: The process of encrypting and decrypting data adds to the overall time it takes to transfer information online. While algorithms can encrypt and decrypt data relatively fast today, it can sometimes be a problem when you want to transfer data quickly.
  2. Key management: Like passwords, managing different keys can be a problem, especially for large organizations. Administrators must decide the level of access each person has to the encryption keys. Thankfully, key management software can be used to simplify the process.
  3. Ransomware: While encryption is designed to protect your data, it can also be used against you. In a ransomware attack, hackers encrypt files and documents on your device, making it inaccessible until you pay a ransom.

Encryption Algorithms and Protocols

Infographic showing different kinds of encryption

There are several ways to encrypt data. We’ve already looked at the difference between symmetric and asymmetric encryption, but there’s more to it.

Encryption depends on protocols and algorithms. An encryption protocol is the broader set of rules that determine the type of cryptographic methods used to protect your data. The algorithm used within that protocol determines how your data is encoded and protected.

In this section, we’ll briefly look at the different algorithms and protocols used in general encryption. These algorithms and protocols work slightly differently. Each has its advantages and disadvantages.

Base encryption algorithms

These are the main algorithms used for data encryption. Several protocols are built on them, which is why we’re referring to them as base encryption algorithms.

Data Encryption Standard

Data Encryption Standard (DES) is one of the earliest encryption standards to be adopted widely. It was developed in the 70s by International Business Machines (IBM). DES supports 64-bit encryption.

The algorithm is no longer considered secure. Instead, you’ll find that many platforms use 3DES instead. With 3DES, your data goes through three stages of encryption and decryption, making it much safer.

Advanced Encryption Standard

Advanced Encryption Standard (AES), also known as the Rijndael algorithm, is the successor of the DES algorithm. There are different versions of AES with varying bits. AES 256-bit is a form of AES encryption that works with 256 bits.

AES 256-bit is considered the most secure form of encryption and is used by most premium VPNs.

Rivest, Shamir, and Adleman

RSA is short for Rivest, Shamir, and Adleman, the people who created this algorithm in the late 70s. It was one of the first public cryptosystems to be used widely. RSA supports asymmetric encryption based on prime numbers. This algorithm is considered quite slow.


Blowfish is a symmetric key encryption cipher that works with 64-bit blocks of data. It was developed in 1993 and is not the most secure algorithm. Twofish, an advanced version of Blowfish that uses 128-bit blocks and 256-bit keys, is recommended over it for use with modern applications. It’s also open source and free.

Communication encryption protocols

The protocols listed below help to maintain privacy by encrypting your data while you use different applications and websites.

Secure Sockets Layer

Although an improved version of Secure Sockets Layer (SSL), Transport Layer Security (TLS), is widely used today, the old name seems to have stuck. The SSL protocol provides a secure connection between your server and the server of any website or web-based service you access.

SSL ensures other parties can’t intercept or modify your traffic. It is widely used and is strong, reliable, and secure.

Pretty Good Privacy

This protocol is useful for encrypting digital messages, such as emails. It was first used in 1991 and is based on asymmetric encryption. With Pretty Good Privacy (PGP), you can encrypt messages and provide emails with a digital signature, so the recipient of a message can be sure you’re its legitimate sender. This protocol is quite popular and very safe.

Secure Shell

Secure Shell (SSH) is an improved version of earlier, weaker protocols. SHH is widely used in corporate networks to enable remote work and file sharing.

Encryption and Digital Certificates

List with magnifying glassAs a regular internet user, it can be quite hard to check whether the encryption used to send messages, payments, and other important data on websites can really be trusted. That’s why digital certificates exist. With a digital certificate, you can be sure that the encryption keys used to send your data have been verified.

There’s an easy way to check if the website you’re using is secure. Simply look for a lock in the left corner of your address bar. If this lock is closed (and possibly green), the encryption between your device and the website is secure — at least, most of the time.

If the lock is open and red, you aren’t using a secure connection. For more information about the digital certificate, you can click the lock and check the certificate. Our article on HTTP and HTTPS connections contains more information about this topic.

The danger of false digital certificates

Unfortunately, checking a website’s digital certificate is not a definitive solution, as some certification authorities (CA) can’t be trusted. Phishing websites are known to have false certificates to make you think they’re safe.

So how can you know for sure whether a website is trustworthy? The best way to do this is to inspect the URL and check the website’s certificate. If you have to enter your personal data somewhere, be extra careful and don’t share sensitive data if there is anything suspicious about a website.

For more information about malicious links and websites, have a look at our article on phishing.

Encryption on Social Media

Encryption on social mediaEnd-to-end data encryption is one of the primary ways that messaging apps protect the privacy of users. WhatsApp, Facebook Messenger, Snapchat, Telegram, Signal, Wire, and many other messaging apps provide end-to-end encryption. Some popular anonymous email providers, such as ProtonMail, also use this form of encryption.

Since 2016, WhatsApp has been using end-to-end encryption to protect the privacy of its users. One of the things that make WhatsApp unique from other messaging apps is that it offers end-to-end encryption by default. You may recognize the message below from your WhatsApp conversations.
WhatsApp end-to-end encryption message

End-to-end data encryption ensures that no one can view your messages, even when it is in transit.

How do I check if my WhatsApp is secure?

You can check whether the encryption on your WhatsApp app is working properly. Every contact you have on WhatsApp has a different encryption code to protect your messages. You can find this code by tapping the name of a contact at the top of a conversation, and then going to “Encryption.”

Only you and the person you’re talking to can access the code. This unique code ensures your messages are only visible to the two of you. You can compare the numbers or scan the QR code to check if your messages are encrypted.

This code changes when you reinstall WhatsApp, change your phone number, or use a different phone.

Encryption With a VPN

VPN shield icon on a dark laptopA VPN secures your internet connection and protects your data. It creates a barrier between you and online threats, such as malicious hackers. A VPN also gives you increased online freedom, allowing you to get around geo-blocks and other restrictions.

VPN providers use encryption to make all this happen. To provide a high level of security and anonymity, they often use complex encryption algorithms and protocols.

Many top VPNs give users the ability to pick from different secure protocols to encrypt their data. These protocols include OpenVPN, WireGuard, L2TP/IPsec, PPTP, IKEv2, and SSTP. We have an article on VPN protocols, where we explain the advantages and disadvantages of each protocol.

NordVPN offers most of these protocols. It’s our highest-ranked VPN for security, functionality, and performance. If you’re looking for a VPN that offers solid encryption, look no further than NordVPN.

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Final Thoughts on Encryption

Encryption is vital in the digital world. Without it, all our private messages, files, and data would be vulnerable to hackers and other prying eyes. It provides an essential layer of security that can help to prevent data breaches.

We recommend using a VPN to complement the encryption and other security provisions on the apps you use and the online platforms you visit.

Encryption: Frequently Asked Questions

If you’d like to learn more, we answer some of the most common questions about encryption below. If there’s anything else you’d like to know about data encryption that we haven’t covered, please let us know in the comment section below!

Encryption is the process of converting plain, readable text into obscure, incomprehensible data. Algorithms are used to encrypt data and protect it from snooping third parties. Read our article about encryption to learn more about how it works.

Encryption scrambles data into unreadable code/alphanumeric strings. These strings can only be decrypted or deciphered using an encryption key. As a result, only the intended recipient with the encryption key can access encrypted data.

Encryption is the bedrock of secure data transmission on the internet. It is used to protect sensitive data on social media and just about every other online platform. Read our article about encryption to learn more about the different types of encryption.

The algorithm and protocol used to encrypt your data determines how secure the information is. Generally, asymmetric encryption, which relies on two sets of keys, is considered safer than symmetric encryption, which uses just only one key. Protocols such as AES and RSA are considered more secure than others like DES, which can be vulnerable to attacks.

While there are many types of encryption algorithms in use today, the three primary ones are:

  1. DES: This is one of the earliest forms of data encryption, developed n the 1970s. Data Encryption Standard (DES) relies on 64-bit encryption, which is not very safe. Its successor, Triple Data Encryption Standard (3DES), is relatively safer.
  2. AES: Advanced Encryption Standard (AES) is arguably the most secure encryption algorithm. It’s used by most premium VPN providers today.
  3. RSA: Named after its founders—Rivest, Shamir, and Adleman—RSA is one of the most preferred algorithms for asymmetric encryption.
Tech journalist
Mohit is a legal and public policy researcher whose work focuses largely on technology regulation. At VPNOverview, he writes about cybersecurity, cryptocurrencies and sports events.